Radio receiving system



Apri s, 1930. -L COHEN 1,753,308 RADIO RECEIVING SYSTEM l Filed Oct. 2, 1925 mw amg lzo Patented Apr. 8, 1930 N UNl'rlzo STATES,

PATENn OFFICE LOUIS COHEN, or WASHINGTON, DISTRICT yor COLUMBIA, AssIGNOR, BY MnsNE AssIeNl MENTS, To FEDERAL' TELEGRAPH COMPANY, A CORPORATION OF CALIFORNIA` y 'Y RADIO RECEIVING- SYSTEM Application filed October 2, 1925. VSerial ANO. 60,120.

This invention relates to `animprovement in antennae for the reception of radio signals.

The object of the invention is a novel and improved form of antenna resonantly respon-4 sive simultaneously tO a number of diderent frequencies. 1 s j Another Object is to provide method and means for the simultaneous operation of several receivers on the same antenna..

I n the reception of radio signals, the elements required are an antenna or an energy collector, tuned circuits, detector and amplis er. For each individual receiver a separate antenna is required. The continuous increase in the number of receivers fused for broadcast reception necessitates a corresponding continuous increase in the number of antennae so that even at the present time *in each large apartment building housing Ymany dwellers, theroof is frequently covered by a network of antennae. vEach individual. antenna means expense in installation and also .requiresattention and frequently diiculties arise in accommodating all who desireto install anten` nee On the roof of the samebuilding for the operation of thelindividual receivers. As time goes on and the use of radio becomes still more widespread, the situation is sure to become more aggravated.

This invention offers a solution to the prob-` lem by providing a method whereby a single antenna may be used forthe simultaneous operation of many receivers, each selecting the particular 4signals it is desired to receive. This is accomplished by fthe use of an antenna which is resonantly responsive'simultaneously to a number of frequencies within a predetermined range of frequencies, and if the different frequencies for which the antenna is thus tuned are close together the antenna will act as an efficient energy collector for practically all the frequencies within the eX- treme limits of the frequencies for which the antenna is tuned. A number of receivers can then be coupled to the antenna and each receiver tuned to select the particular signal desired. Such an antenna is particularly Y adapted for use on large apartment buildings adjusted to be in resonance for frequencies within the broadcasting range, and thus make it available for broadcast reception by all the tenants inj the building. Further, since only one vantenna suffices for an entire: building, more space will be available to build an antenna covering va larger area which would be a more efficient Venergy collector.

In order that the invention may be fully understood, attention `is'directedto the accompanying drawings forming a part of the specification, in which:v i l Figure 1 shows an embodiment of my in vention in which the tuning elements ofthe antenna are coupled to each other through inductances and the various receivers are coupled to the antennainductively; Fig. 2 is an'' otherembodiment of my invention in which the tuning elements of the antenna are coul pledthrough condensers, and the vvarious receivers are Y also ,Y coupled to the antenna through condensers. I I-Iaving particular reference'to the drawings in which like reference characters designate similar' parts, in Fig. 1, thejanntenna l, preferablya horizontal `type of large area, is connected through thelead 2vto the series of couplinginductances 3,74,V 5, and 6, the circuitsy system A, and ground`21. If the antenna is placed on the'roof of a build# ing, the lead2 is made long enough so as to bring the couplinginductance coils to any desired level of the building.v vEach of the coupling coils v3, 4, 5,7and `Gis shunted by a very small condenser' 43 so that when any inductance coil is opened or disconnected the antenna circuit will not be broken. A series of tuning receiving circuits indicated by 23, 24; 25 26; 27, 28; and 29, 30; and associated detectors and amplifiers'designated by 44, arecoupled to the coupling inductances in the antenna circuit.l The circuit system A which consists of a series of similar sections, each comprising aseries inductance and a shunt circuit of an inductance and capacity in parallel, functions to effect the multiple tuning of the antenna system. In my, copending application` Serial No. 53,714, filed August 31, 1925, I have shown that a circuit system as thatindicated by A, responds resonantly to a number of frequencies, the extreme' fre- V l 1 fm2wird where L1 designates the series inductance,

and L2 and C2 the inductancesand capacity f of the shunt circuit. It is evident that the range of frequencies for which the system is i L2 in resonance depends on the ratio of this ratio can be fixed to cover any desired range, which may be the broadcasting rangev now in use. The number of frequencies Within that range for which the system is in resonance is determined by the number of sections used. By increasing the number of sections the system Will be in resonance for a larger number of frequencies and thus bring the resonance frequencies closer together which Would give the effect of approximate tuning for all the frequencies within the range for which the system is adjusted. This antenna system, therefore, will respond resonantly to signals of all ,frequenciesvvithin a certain range of frequencies. The several receiving circuits are each Whose frequency is Within the 'range of frequencies for Which the antenna system is tuned. By this arrangement la number of vreceivers may be connected up to one antenna, each one operating independently and selecting the particular signal desired.

For purposes of illustration I have shown in the figure only four receiving circuits connected to the antenna, but this should not be taken as a limitation upon the system for the method is Well adapted for use in the operation of a large number of receivers connected to the same antenna. Also, the tuning circuit system A is shown here as comprising five sections. This again is merely illustrative. The more sections used the closer approach to tuning for all frequencies within a given range is obtained and the more satisfactory the system will operate.

Figure 2 is similar to Fig. 1 except for modications in the matter of couplings. The receiving circuits are coupled through condensers to the antenna. Each of the receiving circuits 23, 24; 25, 26; 27, 28; and 29, ;4 are connected through small condensers across a series condenser in the antenna. This type of coupling may be called electrostatic coupling which takes the place of the electromagnetic coupling or inductive coupling shown in connection With Fig. l. Also, in the tuning circuit system A, the shunt elements are connected through small condensers instead of nductances as in the case of Fig. 1. The principles of operation of this system are similar to those described in connection with Fig. l.

What I claim and desire to secure by Letters Patent of the United States is as follows:

l. In a multiplex radio receiving system comprising an antenna-ground circuit, a circuit system connected in series vvith the said antenna, saidk circuit system consisting of a number of sections, Aeach section comprisinga series inductance and a pair of tuned circuits, each tuned lcircuit including an inductance shunted by a'condenser, said tuned circuits all being connected together and disposed in series in said antenna and ground circuit to effect a multiple' tuning of the antenna, a plurality of separate receiving circuits associated With the said antenna and independent of the aforesaid sections, each of saidreceiving circuits being adjusted for resonance for one of the frequencies Within the range of frequencies for which the antenna system is tuned, and separate detectors and amplifiers associated With each of saidreceiving circuits.

2. In a multiplex radio receiving system comprising an antenna, a circuit system associated With the said antenna, said circuit system comprising a number of sections, each section-consisting ofan impedance element and tWoloop circuits, said loop circuits be-V ing directly connected together at one end and having their oppositeV ends connected through said impedance element With the adjacent sections having a loop circuit in common to effect multiple tuning of the antenna, several additional inductances in series in the antenna circuit and a separate receiving circuit coupled to` each of the said additional in# ductances, each of the said receiving circuits being tuned to a frequency Within the frequency range for Whichlthe vantenna system is tuned and separate detectors and amplifiers associated with each of the receiving circuits, said receiving circuits each being independe ent ofthe sections of saidcircuit system.'

3. In a multiplex radio receiving system comprising an antenna, a circuit system associated With the said antenna, said circuit system comprising a number of sections,each section kconsisting of an impedance element and tvvo loop circuits, said loop circuits being directly connected together at one end and having their opposite ends connected through said impedance element With the aforesaid sections having a loop circuit in common and related to each other to effect multiple tuning of the antenna, several additional inductances in series in the antenna circuit, each'of the said additional inductances being shunted by a condenser, and an independent receiving circuit separately coupled to each of the said additional inductances, each of the said receiving circuits being tuned lto a frequency Within the range of frequencies for which Ythe antenna system is tuned and separate'deof impedance units, the electrical constants of A the elements of each of the said independent circuits and the couplings between them being so adjusted as to make the .said antenna circuit system simultaneously resonant for several frequencies, several independent receiving circuits separately coupled to the said antenna, and each of the said independent receiving circuits being adjusted in resonance for one of the frequencies for which the said antenna circuit system is tuned.

In testimony whereof I aiix my signature.

LOUIS COHEN. 

